I had a brand new 2006 x5 a couple years back.
I LOVED IT!
It handles awesome!! The 2008 body style is a little different in comparison, but you cannot go wrong with the BMW. They make great driving cars!
My boyfriend really likes his Dad's X5, he was going to get that until he found out about the X6-now he's waiting for that to come out. I suppose because he was between an X5 and Porsche this suits him well. Little bit more body to it, not sure how I feel about it just yet.
I heard some of the new BMW are having major electrical issues though so you might want to check if it includes the X5s as well.